fix #11691: FP throwInNoexceptFunction with if constexpr in template (#6962)

Author: ludviggunne

Makefile

@@ -511,7 +511,7 @@ $(libcppdir)/checkersidmapping.o: lib/checkersidmapping.cpp lib/checkers.h lib/c
 $(libcppdir)/checkersreport.o: lib/checkersreport.cpp lib/addoninfo.h lib/checkers.h lib/checkersreport.h lib/config.h lib/errortypes.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/standards.h lib/suppressions.h
 	$(CXX) ${INCLUDE_FOR_LIB} $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $(libcppdir)/checkersreport.cpp
 
-$(libcppdir)/checkexceptionsafety.o: lib/checkexceptionsafety.cpp lib/addoninfo.h lib/check.h lib/checkexceptionsafety.h lib/config.h lib/errortypes.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/sourcelocation.h lib/standards.h lib/suppressions.h lib/symboldatabase.h lib/templatesimplifier.h lib/token.h lib/tokenize.h lib/tokenlist.h lib/utils.h lib/vfvalue.h
+$(libcppdir)/checkexceptionsafety.o: lib/checkexceptionsafety.cpp lib/addoninfo.h lib/astutils.h lib/check.h lib/checkexceptionsafety.h lib/config.h lib/errortypes.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/smallvector.h lib/sourcelocation.h lib/standards.h lib/suppressions.h lib/symboldatabase.h lib/templatesimplifier.h lib/token.h lib/tokenize.h lib/tokenlist.h lib/utils.h lib/vfvalue.h
 	$(CXX) ${INCLUDE_FOR_LIB} $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $(libcppdir)/checkexceptionsafety.cpp
 
 $(libcppdir)/checkfunctions.o: lib/checkfunctions.cpp lib/addoninfo.h lib/astutils.h lib/check.h lib/checkfunctions.h lib/config.h lib/errortypes.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/smallvector.h lib/sourcelocation.h lib/standards.h lib/suppressions.h lib/symboldatabase.h lib/templatesimplifier.h lib/token.h lib/tokenize.h lib/tokenlist.h lib/utils.h lib/valueflow.h lib/vfvalue.h

lib/checkexceptionsafety.cpp

@@ -24,6 +24,7 @@
 #include "settings.h"
 #include "symboldatabase.h"
 #include "token.h"
+#include "astutils.h"
 
 #include <list>
 #include <set>
@@ -239,7 +240,6 @@ void CheckExceptionSafety::catchExceptionByValueError(const Token *tok)
                 "as a (const) reference which is usually recommended in C++.", CWE398, Certainty::normal);
 }
 
-
 static const Token * functionThrowsRecursive(const Function * function, std::set<const Function *> & recursive)
 {
     // check for recursion and bail if found
@@ -251,6 +251,7 @@ static const Token * functionThrowsRecursive(const Function * function, std::set
 
     for (const Token *tok = function->functionScope->bodyStart->next();
          tok != function->functionScope->bodyEnd; tok = tok->next()) {
+        tok = skipUnreachableBranch(tok);
         if (Token::simpleMatch(tok, "try {"))
             tok = tok->linkAt(1);  // skip till start of catch clauses
         if (tok->str() == "throw")

oss-fuzz/Makefile

@@ -198,7 +198,7 @@ $(libcppdir)/checkersidmapping.o: ../lib/checkersidmapping.cpp ../lib/checkers.h
 $(libcppdir)/checkersreport.o: ../lib/checkersreport.cpp ../lib/addoninfo.h ../lib/checkers.h ../lib/checkersreport.h ../lib/config.h ../lib/errortypes.h ../lib/library.h ../lib/mathlib.h ../lib/platform.h ../lib/settings.h ../lib/standards.h ../lib/suppressions.h
 	$(CXX) ${LIB_FUZZING_ENGINE} $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $(libcppdir)/checkersreport.cpp
 
-$(libcppdir)/checkexceptionsafety.o: ../lib/checkexceptionsafety.cpp ../lib/addoninfo.h ../lib/check.h ../lib/checkexceptionsafety.h ../lib/config.h ../lib/errortypes.h ../lib/library.h ../lib/mathlib.h ../lib/platform.h ../lib/settings.h ../lib/sourcelocation.h ../lib/standards.h ../lib/suppressions.h ../lib/symboldatabase.h ../lib/templatesimplifier.h ../lib/token.h ../lib/tokenize.h ../lib/tokenlist.h ../lib/utils.h ../lib/vfvalue.h
+$(libcppdir)/checkexceptionsafety.o: ../lib/checkexceptionsafety.cpp ../lib/addoninfo.h ../lib/astutils.h ../lib/check.h ../lib/checkexceptionsafety.h ../lib/config.h ../lib/errortypes.h ../lib/library.h ../lib/mathlib.h ../lib/platform.h ../lib/settings.h ../lib/smallvector.h ../lib/sourcelocation.h ../lib/standards.h ../lib/suppressions.h ../lib/symboldatabase.h ../lib/templatesimplifier.h ../lib/token.h ../lib/tokenize.h ../lib/tokenlist.h ../lib/utils.h ../lib/vfvalue.h
 	$(CXX) ${LIB_FUZZING_ENGINE} $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $(libcppdir)/checkexceptionsafety.cpp
 
 $(libcppdir)/checkfunctions.o: ../lib/checkfunctions.cpp ../lib/addoninfo.h ../lib/astutils.h ../lib/check.h ../lib/checkfunctions.h ../lib/config.h ../lib/errortypes.h ../lib/library.h ../lib/mathlib.h ../lib/platform.h ../lib/settings.h ../lib/smallvector.h ../lib/sourcelocation.h ../lib/standards.h ../lib/suppressions.h ../lib/symboldatabase.h ../lib/templatesimplifier.h ../lib/token.h ../lib/tokenize.h ../lib/tokenlist.h ../lib/utils.h ../lib/valueflow.h ../lib/vfvalue.h

test/testexceptionsafety.cpp

@@ -361,6 +361,17 @@ class TestExceptionSafety : public TestFixture {
         // avoid false positives
         check("const char *func() throw() { return 0; }");
         ASSERT_EQUALS("", errout_str());
+
+
+        // #11691: FP throwInNoexceptFunction with if constexpr in template
+        check("template<bool IsNoThrow>\n"
+              "static void foo(size_t Size) noexcept(IsNoThrow) {\n"
+              "    if constexpr (!IsNoThrow) {\n"
+              "        throw std::bad_alloc();\n"
+              "    }\n"
+              "}\n"
+              "foo<true>(123);\n");
+        ASSERT_EQUALS("", errout_str());
     }
 
     void unhandledExceptionSpecification1() { // #4800